Experiential Effects On Agonistic Behavior in the Paradise Fish, Macropodus Opercularis

Abstract

The effects of prior dominance experience on agonistic behavior were investigated in male paradise fish, Macropodus opercularis, with particular reference to the social conditioning hypothesis. The subjects had only limited social experience prior to the pre-test treatments; their pre-test dominance histories were controlled experimentally, through rigged contests (based on relative size). Following the pre-test conditioning treatments, the treated fish were paired with naive siblings of the same standard length, and subjected to a battery of four tests: two measures of aggressiveness, one of reactivity and one of social dominance. The latter consisted of a dyadic encounter with a naive sibling in a neutral aquarium. Four separate experiments were conducted, each exploring a different parameter of social dominance. It was found that negative dominance experience resulted in a significant decrement in subsequent dominance success and in increased reactivity levels, but had no influence on the measures of aggressiveness. Positive dominance experience had no effect on any of the response measures. The implications of the asymmetry in the effects of dominance experience (particularly with regard to subsequent dominance scores) for the social conditioning hypothesis and the associationist paradigm in general, as it applies to agonistic behavior, were explored. It was concluded that the social conditioning hypothesis cannot account for the results obtained here or for those of related studies. The relationships between the measures of aggressiveness and the measure of social dominance were also discussed.